1. Field of the Invention
The present invention relates to a bag having a degas structure and a method for producing the bag.
2. Description of the Related Art
A bag made of synthetic resin has been conventionally proposed for receiving granules or grains such as cereals or manure or fertilizer. The bag is of a type which is obtained by a laminate method of overlapping a plurality of pieces of resin film together and melt-bonding (sealing) their ends with each other or of a type which is obtained by an inflation method of blowing synthetic resin from an annular slit formed in a mold together with air.
However, when granules are filled in the bag made of synthetic resin, if the air introduced into the bag together with the granules is not removed but sealed, the bag is kept under the inflated condition due to the air to cause to collapse of the load alignment or to reduce the receiving space.
Accordingly, there are various conventional approaches to remove the unnecessary air from the bag by providing holes (punched holes) in the bag and utilizing the holes as degas holes for removing the air from the bag or by providing a portion, which is not subjected to the thermal bond, to a thermal bond portion upon molding the bag and utilizing the non-thermally bonded portion as degas holes.
However, when the granules are filled into the bag actually, the degas holes provided in the bag made of synthetic resin are deformed (expanded) due to the filling pressure of the granules to cause to leak the content or the degas holes are clogged by the pseudo-bond by the blocking of the film, resulting in non-function of the degas holes. As a result, it is impossible to well discharge the unnecessary air. Furthermore, in view of the structure, there is a problem that water, dust or bugs are likely to enter into the interior of the bag from the outside. Thus, the conventional bag suffers from various disadvantages.